Kuse Naoyuki, Kamio Koichiro, Azuma Arata, Matsuda Kuniko, Inomata Minoru, Usuki Jiro, Morinaga Akemi, Tanaka Toru, Kashiwada Takeru, Atsumi Kenichiro, Hayashi Hiroki, Saito Yoshinobu, Seike Masahiro, Gemma Akihiko
Department of Pulmonary Medicine and Oncology, Graduate School of Medicine, Nippon Medical School.
J Nippon Med Sch. 2020 Jul 13;87(3):118-128. doi: 10.1272/jnms.JNMS.2020_87-302. Epub 2019 Nov 28.
Although aberrant proliferation and activation of lung fibroblasts are implicated in the initiation and progression of idiopathic pulmonary fibrosis (IPF), the underlying mechanisms are not well characterized. Numerous microRNAs (miRNAs) have been implicated in this process; however, miRNAs derived from exosomes and the relevance of such miRNAs to fibroblast-to-myofibroblast differentiation are not well understood. In this study, we attempted to identify exosome-derived miRNAs relevant to fibrosis development.
Using miRNA array analysis, we profiled exosome-derived miRNA expression in sera of C57BL/6 mice exhibiting bleomycin-induced pulmonary fibrosis. After validating a selected miRNA by quantitative reverse-transcription polymerase chain reaction, its effect on fibroblast-to-myofibroblast differentiation was investigated in human lung fibroblasts. Furthermore, we determined the role of the selected miRNA in an in vivo model of pulmonary fibrosis.
MiRNA array analysis revealed that miR-22 expression was increased by up to 2 fold on day 7 after bleomycin treatment compared with that in vehicle-treated mice. In vitro, miR-22 transfection suppressed TGF-β1-induced α-SMA expression. This was mediated via inhibition of the ERK1/2 pathway. Baseline α-SMA expression was increased upon miR-22 inhibitor transfection. Furthermore, miR-22 negatively regulated connective tissue growth factor expression in the presence of TGF-β1. In vivo, administration of a miR-22 mimic on day 10 after bleomycin challenge ameliorated pulmonary fibrosis lesions accompanied by decreased α-SMA expression in the model mice.
Exosomal miR-22 modulates fibroblast-to-myofibroblast differentiation. The present findings warrant further study, which could shed light on miR-22 as a novel therapeutic target in IPF.
尽管肺成纤维细胞的异常增殖和激活与特发性肺纤维化（IPF）的发生和发展有关，但其潜在机制尚未完全明确。众多微小RNA（miRNA）参与了这一过程；然而，源自外泌体的miRNA及其与成纤维细胞向肌成纤维细胞分化的相关性尚不清楚。在本研究中，我们试图鉴定与纤维化发展相关的外泌体来源的miRNA。
使用miRNA阵列分析，我们分析了博来霉素诱导的肺纤维化C57BL/6小鼠血清中外泌体来源的miRNA表达。通过定量逆转录聚合酶链反应验证所选miRNA后，研究其对人肺成纤维细胞向肌成纤维细胞分化的影响。此外，我们确定了所选miRNA在肺纤维化体内模型中的作用。
miRNA阵列分析显示，与载体处理的小鼠相比，博来霉素处理后第7天miR-22表达增加了2倍。在体外，miR-22转染抑制了TGF-β1诱导的α-SMA表达。这是通过抑制ERK1/2途径介导的。miR-22抑制剂转染后，基线α-SMA表达增加。此外，在存在TGF-β1的情况下，miR-2负调控结缔组织生长因子的表达。在体内，博来霉素攻击后第10天给予miR-22模拟物可改善肺纤维化病变，模型小鼠中α-SMA表达降低。
外泌体miR-22调节成纤维细胞向肌成纤维细胞的分化。目前的研究结果值得进一步研究，这可能为miR-22作为IPF的新型治疗靶点提供线索。
